Wet ready-mix concrete begins to set shortly after water is added, typically giving a workable window of 90 minutes or less. This severely limits transport distance and makes cross-border shipment of wet mixes impractical in most cases. Trade in this category is therefore dominated by dry preblended mortars, grouts, and specialty mixes that are mixed with water at the job site.

Nonrefractory mortars and concretes are formulated for standard construction applications and are not designed to withstand sustained high temperatures. Refractory concretes and castables, by contrast, use high-alumina or other heat-resistant binders and aggregates for use in furnaces, kilns, and industrial high-heat environments. The distinction affects both NAICS industry assignment and HTS tariff classification.